There is a virtual link configured over area 1 on R2 and R3.
R1 has 8 ospf interfaces with contiguous IPs 60.60.X.3 X=0..7
R2 has a range configured to condense them from area 0 into area 1:
router ospf 1
area 0.0.0.0 range 188.8.131.52 255.255.248.0
When the virtual link is up, R2 redistributes ALL 8 routes as LSAs into area 1! (seen with show ip ospf database)
When I disable the virtual link on R3, R2 does the condensation and only 1 LSA is advertised into area 1.
Do you know what document states that if on an ABR like R2, if the destination area like area 1 has a virtual link up in it, the routes are NOT condensed INTO it? (this seems to be the exact cisco behaviour)
There might be some common sense logic that when the virtual link is up, all routers are in area 0 and no condensation is needed, but I would like to understand the theory also.
I don't have a link for you explaining this behavior. But, I am sure there has got to be an RFC or Cisco document that has this documented.
I can try to explain this behavior though. What you are seeing is the normal behavior. By virtue of having the virtual-link R3 becomes an ABR. As you may know, all OSPF routers in an area would have an identical database. As both R2 and R3 are connected to the backbone (area 0) if R2 were to summarize the route(s) to R3, when the virtual link is up, that would violate the OSPF requirement of an identical database of area 0.
When you do not have a virtual link the 'area range' command works as it supposed to by summarizing the route into area 1.
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